Just click on the Demo Content Setup button and read the instructions:

Now click on the I agree, continue demo content setup button and the installation process will start (this process may take 5 or 10 minutes depends on your server performance):

When finished, you will see message like this:

Now your site will be same as our demo site.

Tips: The above step will add demo content but it will not add sliders and other settings. Please follow steps given below to setup slider and other settings so you will get exact same copy of our demo site.